DE1569387C3 - Molding compounds made from olefin polymers - Google Patents

Description

The invention relates to molding compositions and their use for the production of moldings which have a Contain α-olefin polymer and certain block copolymers. It is known by the addition of the impact resistance of α-olefin polymers on certain natural and synthetic rubbers modify and sometimes improve. While the molding compositions produced in this way are limited If, however, their impact resistance has improved, that improvement usually occurs at the expense of other properties. Thus, when bending a rod or a foil, these ordinary ones emerge Rubber mixtures a significant lightening of the preparation at the stressed point on what is commonly referred to as "whitening." If the bending stress decreases, then it remains this lightening usually backs up or only partially disappears, so that the object in appearance and the mechanical properties are damaged. The exact cause of this phenomenon is not known for sure. However, it is likely due to phase separation or the occurrence of Microcracks in the preparation at the point of maximum stress.

Molding compositions are known from German Auslegeschrift 1 099 161 which contain a polypropylene with a molecular weight 50,000 to 500,000, ie more than 5000, and contain a butyl rubber, which is a copolymer is made of isobutylene and a little isoprene. The unsaturation of this butyl rubber is caused by the The amount of polymerized isoprene is determined because it consists of a saturated isobutylene chain, which is arbitrary is interrupted by isoprene residues. According to column 1, lines 48 to 54, are more unsaturated Rubbers, especially butadiene-styrene copolymers, for an improvement in the properties of polypropylene is far less suitable.

According to the invention molding compositions are created which have a content of α-olefin polymer with a Molecular weight of at least 5000 and preferably more than 10,000 and of a copolymer and have certain advantages over the prior art. The invention Molding compositions that are between 2.5 and 97.5 percent by weight, based on the polymers, of one α-olefin polymer with an average molecular weight of at least 5000 and a copolymer are characterized in that the copolymer is a hydrogenated block copolymer of the general formula A - B - A from a polymer of an aromatic alkenyl hydrocarbon A with an average molecular weight between 4000 and 115,000 and one polymerized conjugated diene hydrocarbon B having an average molecular weight between 20,000 and 450,000, the polymer A 2 to 33 percent by weight of the block copolymer and the remaining unsaturation of the block copolymer is less than 30.

"Residual unsaturation" is the unsaturation of the polymer according to its hydrogenation, · - treatment compared to its original V unsaturation. The degree of unsaturation is determined according to known analytical methods. The present invention is particularly concerned with polymeric preparations of α-olefin polymers, in which the α-olefin has 2 to 6 carbon atoms per molecule and the average molecular weight of the polymer is more than approximately 10,000, with block copolymers are connected, in which, before the hydrogenation, the terminal blocks A according to the above formulation polymerized vinyl aromatic hydrocarbons and the central block polymerized conjugated Contain dienes with 4 to 10 carbon atoms. This was the block copolymer mentioned to reduce the unsaturation to less than 20% of its original value, thus up to hydrogenated to residual unsaturation less than 20, so that the average molecular weight of the central conjugated diene polymer block is between about 50,000 and 300,000. The advantages of using the Preparations occur vary with the nature and amount of their components, including an improvement in tensile strength, a substantial improvement in impact resistance low temperature, as well as the reduction or disappearance of the whitening of the preparation during their use. The use of a hydrogenated one is particularly preferred in this regard Block copolymer A - B - A from one polymer of a monovinyl-substituted aromatic hydrocarbon A having an average Molecular weight between 8,000 and 60,000 and a polymerized conjugated diene hydrocarbon B having 4 to 10 carbon atoms with an average molecular weight between 50,000 and 300,000, the remaining unsaturation being less than 20, as a copolymer in the Molding compounds.

The alpha-olefin polymers to be used according to the invention are polymers of ethylene or higher olefins and can be atactic, syndiotactic or have an isotactic structure. The beneficial effects are particularly remarkable when using alpha-olefin poly-

merizates which have at least about 55% a crystalline structure, and especially then, when the average molecular weight of the alpha olefin polymer is greater than about 30,000 amounts to.

The alpha-olefin copolymers cannot only contain homopolymers, such as polyethylene or polypropylene, but copolymers can also be used preferably of the plastic (non-elastomeric) type, such as the non-elastomeric Copolymers of ethylene and propylene. These are usually copolymers with a relative low propylene content, which contain, for example, 85 to 98 ethylene and the remainder propylene units. The molecular weight of the polymers can over the entire range from about 500 up to as much vary like 2 million or even more. However, the polymers are of the greatest importance molecular weight greater than 10,000, and preferably greater than about 30,000, usually 200,000 to 500,000. The most effective combinations range from 2.5 to 97.5, and preferably from 10 to 90 parts by weight of α-polymer to 100 parts by weight of the preparation.

The use of block copolymers to improve the properties of poly-α-olefins is particularly surprising since German Auslegeschrift 1099 161, for example, butadiene-styrene copolymers labeled as unsuitable for this purpose. The properties of those used according to the invention Block copolymers can, for. B. be adjusted by hydrogenation, what after the German Auslegeschrift 1 099 161 is not possible at will because the unsaturation of the butyl rubber used there compared to that built into the copolymer Isoprene amount is determined.

The block copolymers used according to the invention are, inter alia, those which before Hydrogenation have the structure A - B - A, in which the polymer blocks A have an average Molecular weight from 4000 to 115,000 and preferably Have 8,000 to 60,000. The monomers from which the terminal polymer blocks are formed are, among other things, alkenyl-substituted aromatic hydrocarbons as well as mixtures the same. The central block can, among other things, be such a, which by polymerization of conjugated Serving is formed with preferably 4 to 10 carbon atoms in the molecule, where the central block average molecular weight between about 20,000 and 450,000, preferably is between about 80,000 and 300,000. An essential feature of these copolymers is their low degree of unsaturation, which is either due to the choice of when forming the block polymer used monomers or achieved by hydrogenation of the same after its formation will. Accordingly, the diene polymer block in the preparations according to the invention has either one his own or is due to such unsaturation hydrogenated having an iodine number between about 0 and 50, and preferably less than about 25 grams Iodine corresponds to 100 g of polymer, in which the UV analysis shows that up to at least 70 percent by weight Cycloalkane units are present.

These block polymers are preferably formed from two types of monomers, the end groups are produced from cyclic vinyl hydrocarbons and the terminal polymer blocks mentioned are essentially non-elastomeric in character, while the central blocks extend through are characterized by elastomeric properties. The block copolymers are even better those in which the terminal blocks prior to hydrogenation are polymer blocks of an aromatic vinyl hydrocarbon having linked to a block of conjugated dienes having 4 to 10 carbon atoms are.

The block copolymers also show a substantial difference in glass transition temperature the terminal and the central block.

The block copolymers are preferably prepared with the aid of those known in this context Catalysts hydrogenated, for example with the help of nickel on kieselguhr and the like, with a reduction in unsaturation of the polymer below the limits given above. The hydrogenation not only confers better compatibility with the olefin polymers, but also a significant improvement in the thermal and oxidation resistance of the block copolymers.

The elastomeric middle parts can originally be made by polymerizing conjugated diolefins, such as butadiene and isoprene or methyl isoprene can be obtained. The non-elastomeric terminal ones Polymer blocks can have and become homopolymers or copolymers preferably from aromatic alkenyl hydrocarbons, in particular from aromatic vinyl hydrocarbons produced, in which a monocyclic or polycyclic aromatic radical is present can.

The block copolymers can in various ways and preferably using Lithium-based catalysts are produced. Used as a catalyst a monolithic hydrocarbon used, then the formation of the block copolymer proceeds according to a sequence of stages, in which the vinyl cyclic hydrocarbon compound with the aid of the lithium-based catalyst is polymerized and the formation of a living polymer arises from a lithium residue is terminated. At least one conjugated diene is then added to the polymerization mixture and the polymerization continued until the desired block length is achieved. Then the Add a second amount of the same or a different cyclic. Vinyl hydrocarbon.

Preferred catalysts, which are ideal for the preparation of the invention. Block polymers suitable include metallic lithium, lithium alkyl compounds and aromatic, compounds containing one or more lithium radicals.

If dilithium initiators are used, the conjugated diene can first be polymerized to form the central block, which is provided with a lithium radical at both ends, and the cyclic alkenyl hydrocarbon can then be added for simultaneous formation of the two terminal blocks . ■ '■ ■ - ■' ■ · ■■■

After maintaining the block copolymer, the same can, if necessary, be used to reduce the unsaturation of the polymer are then hydrogenated below the maximum numerical values given above. The received according to this and other procedures

NEN products that can be processed in the preparations according to the invention include essentially linear block copolymers in which the terminal groups prior to hydrogenation for example polymer blocks made of styrene and the central block polymerized isoprene or butadiene are. Provided that the hydrogenation causes essentially complete saturation of the molecule is achieved, the product can be, for example, a saturated polymer in which the terminal Groups contain polymerized vinylcyclohexane, while the central elastomeric part contains ethylene-propylene elastomers having. If the hydrogenation is not complete, then the end product is opposite modified this simple fully saturated example. The terminal groups include, for example in the first case saturated polymers, while now a certain small amount of unsaturated Leftovers may be left over. The same applies to the elastomeric central part.

Another essential advantage of the preparations according to the invention can be found in the fact again that these special block copolymers are used to achieve their maximum elastomeric properties do not require chemical vulcanization. As a result, there is no chemical vulcanization process during the implementation according to the invention even during the production of the used Components required.

In the case of preparations that can be used as thermoplastics, the amount of the modifying Block copolymers usually less than 40%. Preferred preparations contain in addition to the alpha-olefin polymer, which is preferably isotactic propylene, 10 to 30 percent by weight of the preparation of the block copolymer, wherein high impact resistance without the occurrence of permanent whitening due to stress occurs. If, on the other hand, elastomeric preparations are to be obtained, then the alpha-olefin polymer represents represents the minor component and amounts to 5 to 30 percent by weight of the preparation. For specific Purposes also provide mixtures with 40 to 60 percent by weight of each type of polymer essential Advantages, especially when high tensile strength is important.

The amount of the individual components does not only depend on the end use in question, but also on the nature of each component. As can be seen from the values given in the exemplary embodiments listed below each pair of the examined components on optimal ranges in which the quantities such as the tensile strength, the low temperature impact resistance and other properties reach maximum. So the tensile strength at ordinary temperature reaches a maximum when each component is approximately the same amount is present. Furthermore, the tensile strength limit Surprisingly increased to a higher value than that of each individual component in the unmodified state. As a result, as little as 0.5 and as much as 99.5 percent by weight can be used each component, based on the polymer mixtures, can be used.

The mixing itself can take place in a known manner which is suitable in this context. A maximum physical incorporation of each polymer into the other is achieved by mixing the solution. In most cases, however, physical mixing devices such as Bunbury mixers or mixing rollers are most suitable. The temperature during the mutual grinding of the essentially solid substances is selected so that the physical properties of the mixture formed reach maximum values. This is usually at a temperature greater than about 170 ⁰ C and preferably greater than about 185 ⁰ C the case.

The preparations can be processed with other components known in this context, including synthetic and natural reinforcing fillers such as carbon black, asbestos, fibers, titanium dioxide, other pigments, plasticizers, flow aids and the like Rubbers are used, for example, as coatings, mechanical goods, · latices, paints, thermally formed objects or insulation. The main advantage thus lies in the improvement of the tensile strength and the modulus of rubber-like preparations without having to be chemically vulcanized and without the disadvantageous appearance of the ^; Becoming white occurs. These include thermoplastic processing methods, according to which the preparations are formed into molded objects such as films, foils, textile covers and the like by injection molding, blowing and compression molding, as well as uses of normal rubber, use as mechanical goods and other production objects.
The formulations can be cast from solvents for the preservation of films or spun for the preservation of fibers and threads. Plastic molding preparations which are accessible to the usual plastic uses can be obtained in particular if the amount of the block copolymer is less than about 50 percent by weight, based on the total preparation, the preparation of the alpha-olefin polymer and the block copolymers being understood. Accordingly, the preparations can, inter alia, also be used for the production of molded objects, mechanical goods, extruded products such as pipes, wire coatings, fibers and the like.

example 1

Isotactic polypropylene with an average molecular weight of approximately 450,000 and an intrinsic viscosity of 2.7 dl / g was modified with a fully hydrogenated block polymer of the configuration: polystyrene-polyisoprene-polystyrene prior to hydrogenation.
The individual average molecular weight of each block was 10,000 to 75,000 - 10000. The mixtures were milled together on rubber rolls at 180 ⁰ C. Tables IA and IB below contain the values which were obtained with samples for the preparation of which the amount of polypropylene to the hydrogenated block copolymer was varied over the entire range - from 100% block polymer to 100% polypropylene.

i 569

Table 1A

Mixtures of the block copolymer with polypropylene (compression-molded sheets, short form D, cut samples; all stretched at 0.5 cm / min.)

mixture
FG

Block copolymer,

Weight percent

Polypropylene.

Yield strength, kg / cm ²

Distance at break, kg / cm ²

Module at 300% elongation ..
Modulus at 500% elongation. '.

Elongation at break ...;

Hardened,% .... ,,, ...

100 0

281 250.

750 20

95

297 500

760

34

90 10

364 650

750 40

85

15th

15.8

376

625

1100

720

60

50

50

94.9

462

1825

2500

750

> 300

195

404

2625

3500

750

> 500

15th

85

237

406

3000

3625

710

> 500

10

90

269

422

3250

3500

870

>

95

297

455

3450

3675

1030

> 600

100

337

394

3650

3900

840

> 600:

Table IB

Mixtures of a block copolymer with propylene (plastic tie rods obtained by injection molding; drawn at 0.5 cm / min.)

Block copolymer,. .. ■■■.,

Weight percent 0 2 5 10 15 25 50 75

Polypropylene, by weight . _K ■

percent., 100 98 95 90 85 75 50 25

Yield strength, kg / cm ² 327 316 299 276 242. 200 118 53.

Yield elongation,% 10 - - - 15 19 ~ 30 ~ 50

Tensile modulus, kg / cm ² -10Ί ⁵ ..... 0.161 - - - 0.105 0.084 0.049 0.021

Flexural Modulus, kg / cm ² x 10 ~ ⁵ 0.168 0.203 0.154 0.21 0.119 0.098 0.049 0.0176

Notched impact strength.

at 0 ⁰ C 0.023 0.018 0.019 0.027 0.050>0.378> 0.81 no break

at 23 ° C 0.052 0.044 0.06 0.14 _ ^: - - -

Shore D hardness 73 73 72 71 69 65 52 38

RockwellR hardness ........ 96 99 95 90 79 65 20. IQ.

Permanent brightening after, .., .., -

Bending low no no no ■ no no no no.

. . merisat of Example 1 through a second Blockmisch- a game ei 2 polymer of the same monomers replaces The effect of the average molecular was 50 in which the average molecular weight of the individual blocks of the Blockmischpölymeri- weight of the individual blocks 5000 - 40000-5000 sates was in comparison to the results of the obi- was. For this purpose, the same polyprogen Example 1 was determined, for which purpose das'Blockmischpol- pylen with an intrinsic viscosity of 2.7 dl / g was used.

Table 2:

Block pymer, weight percent 100 85

Polypropylene, percent by weight ₍ 0 15

Yield strength, kg / cm ² no flow no flow

Tensile strength, kg / cm ^2. ,, .90, 93

Module at 300% elongation, -

% .. X V. '225 450

Module at 500% elongation.

% ..: ... '; ■' -350 750

Elongation at break,%.: ....... 1030 850

75 50 ;, i5. ",. 10 Q 25th 50 "85:;. 90 .!. i.ioö 24.6 253 249.6 567; 95 255 . -77. . ; --- 875 - ■ "' - ' 1200 ■ 740 45 60 ^; 8Ö

309 5) 7/497

I 569 387

continuation

10

Hardened,% 33 80 120 18 22 33

Shore λ hardness 46 57 82 90 - -

Yield strength, kg / cm ² ■ 253 327

Flexural Modulus, (psi) 0.112 0.168

kg / cm ² -10- ⁵ (1.6) (2.4)

Notched Impact Strength, mkg / cm

O ⁰ C 0.022 0.023

23 ° C 0.073 0.052

Shore D hardness .... 69 73

Rockwell R - hardness 84 96.

... 15 average molecular weight of the individual blocks

Example i. Was 10,000-50,000-10,000.

A third block copolymer was common. Table 3 B contains the results, the

sam with the same polypropylene were used and obtained if a block copolymer

mixtures thereof according to Example 1 were used in the same block arrangement in which

represents. The 20 chem obtained with this third polymer, the molecular weight of the blocks 15,000 -

Examination results are shown in Table 3A together - 100,000-15,000. The values in Table 3 C

set. For this polymer were the same correspond to a molecular weight of the blocks of

Chen monomers used, but the through 20,000 - 100,000 - 20,000.

Table 3A

Block polymer, percent by weight 100 85 75 50 15 10 .0

Polypropylene, weight percent 0 15 25 50 85 90 100

Yield strength, kg / cm ² no flow no flow 39.1 '118 265 265

Tensile strength, kg / cm ² 439 471 504 439 - -

Module at 300% elongation,

% '. 625 1050 1350 2050 - -

Module at 500% elongation,

%; 1850 2400 220 2675 - -

Elongation at break, % ............. 610 660 690 710> 100 80

Hardened,%: 24 68 140> 200 70 40

Shore A hardness 69 78 82 93> 100> 100

. Compression molded 10 '/ 200 ⁰ C, cut, short form D

Tensile Samples - drawn at 20 "/ min...

Yield strength, kg / cm ² 263.6 327 "..

Flexural modulus, kg / cm ² x 10 ~ ⁵ .; ... 0.119 0.168

Notched Impact Strength, mkg / cm

0 ⁰ C 0.028 0.023

23 ° C ..... ν .., ....; ^:: · ". 0.070 0.052

ShoreD, - hardness ....... .... . . _; ; 69 73 :;

RockwellR - hardness ........:. . ■. 87 96

ASTE injection molded tie rods -; . -

Pulled 0.2 '' / min.

Table 3B

Block polymer, weight percent 100 85 75, 50 _: .:;

Polypropylene, weight percent 0 15. , 25.; _; . 50

Yield strength, kg / cm ² _v . no flow, no flow 35.2. ;. .. 89.6. ..-,

Tensile strength, kg / cm -320 '400 457 ^; / '' 445. ■. ' ^

Modulus at 300% elongation, kg / cm ² 21.1 75.6 95, ^? ' 135 V ^ .. ¹

Modulus at 500% elongation, kg / cm ^2. ··· (35.2 116 142 '"170

Elongation at break,% 710 710 - 750. ,. . 770. , ■

Hardened,%, .. 018 60 100> 300

ShoreA hardness.;. : 64 79 84 96 ■ · ■ '

Table 3 C

Block polymer, percent by weight 100 85 75 50

Polypropylene, weight percent 0 15 25 _t , 50

Yield strength, kg / cm ² no flow no flow 31.6 95

Tensile strength, kg / cm ² 397 422 471 404

Module at 300% elongation, kg / cm ² 28 65 75 128

Modulus at 500% elongation, kg / cm ² 42.2 98 119 156

Elongation at break,% 900 825 850 850

Hardened,% 32 115 175> 400

Shore A hardness 71 86 88 96

Compression molded 10 '/ 200 ⁰ C, cut short form D
Tensile Samples - drawn at 20 "/ min.

Example 4

Mixtures of the block copolymer from Example 1 with polyethylene having the following properties were produced. The preparation of the mixtures was determined in a rubber mill at 180 ⁰ C. The same 10 minutes at 160 ° C were formed. The following properties were obtained for the various mix preparations:

Table 4

U V sample X Y Z I. 95 90 W. 75 50 0 100 5 10 85 25th 50 100 0 14th 10.5 '15 12.25 26.25 66.5 14th 30.8 322 14th 295 231 92.75 290 26.25 26.25 313 33.25 50.75 71.75 28 49 49 31.5 56 76.75 77 73.5 755 795 59.5 800 795 600 645 20th 30th 740 65 200 500 18th 66 66 40 70 82 93 65 68

Block copolymer, weight percent polyethylene, weight percent ...

Yield strength, kg / cm ²

Tensile strength, kg / cm ²

M ₃₀₀ , kg / cm ²

M ₅₀₀ , kg / cm ²

Elongation at break,%

Hardened,%

Shore B hardness.

Claims (1)

Claim: Molding compositions ^T which contain between 2.5 and 97.5 percent by weight, based on the polymers, of an α-olefin polymer with an average molecular weight of at least 5000 and a copolymer, characterized in that the copolymer is a hydrogenated block copolymer of the general formula A - B-A consists of a polymer of an aromatic alkenyl hydrocarbon A with an average molecular weight between 4,000 and 115,000 and a polymerized conjugated diene hydrocarbon B with an average molecular weight between 20,000 and 450,000, polymer A representing 2 to 33 percent by weight of the block copolymer and the residual unsaturation of the block copolymer is less than 30.